#define N 4
#include <stdio.h>
main()
{
    int a[N][N]={1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16};
    int i,sum1=0,sum2=0;
    for(i=0;i<N;i++)
    { 
        sum1+=a[i][i];
        sum2+=/**/a[i][N-i]/**/;
    }
    printf("sum1=%d\nsum2=%d\n",sum1,sum2);
    return 0;
}